For E, today, we have the Euchee language.
The Euchee (or Yuchi) language is spoken by people from the Euchee tribe, who now live in Oklahoma, USA. As of 2013, four fluent Euchee speakers remain, and though there have been significant efforts to revive the language among the community, the language is, according to UNESCO, classed as being critically endangered.
These methods to revive the language must not remain discounted, however. The Euchee Language Project (the people behind the video above) has been set up in Oklahoma and offers classes to adults and children designed to teach them about the language and Euchee culture. These include immersion classes, as well as classes to help parents learn the language to help their children. There seems to be a concerted effort behind saving and spreading the Euchee language, but with all the fluent speakers being aged over 80 now, and English being such a dominant language in the USA, this will be an uphill struggle for years to come.
Resources to learn Euchee
The Yuchi Primer: A Brief Introductory Grammar
Euchee/Yuchi Language Project
Our Mother Tongues: Euchee
Cultural Survival: The Yuchi House – A Storehouse of Living Treasure